There is known apparatus adapted for aerosolizing a fluid such as medicine, that is stored in a container along with high pressure gas as propellant, through a valve fixed to an inlet of the container. The apparatus of this type has conventionally utilized a specific fluorocarbon (flon) as propellant. At present, the apparatus tends to use hydrofluorocarbon HFC134a as an alternative of the specific flon with increasing concern about environmental protection. However, HFC134a influences not ozonosphere but global warming not less than one thousand times the degree caused by CO.sub.2. Thus, if HFC134a is used with great frequency, it seems that serious environmental problem occurs. Accordingly, use of CO.sub.2 gas or inert gases, for instance, nitrogen, helium, neon, krypton, xenon and radon, acting as aerosol propellant, is at present proposed.
In the case of using such gases as propellant, it is required to liquefy or compress the gases for reducing a size of container as well as the flon conventionally used. The liquefied gases have a high vapor pressure. For example, liquefied CO.sub.2 gas has vapor pressure of 60 kgf/cm.sup.2 at 20.degree. C. It is also desirable that inert gases are liquefied or compressed under pressure of not less than 50 kgf/cm.sup.2 in order to increase volumetric efficiency thereof. Japanese Patent Application First Publication No. 8-141450 discloses an aerosol using such liquefied gas.
The liquefied gas as propellant to be filled in the container has high vapor pressure as described above. The vapor pressure within the container tends to rapidly increase in response to even slight temperature rise of the ambient atmosphere. Therefore, such the aerosol must be handled with considerable care.
The above-described conventional art discloses a gas-emitting valve and an aerosol with the gas-emitting valve, including a gas cartridge that stores fluid and liquefied CO.sub.2 gas as propellant. The gas-emitting valve is secured to an open end of the gas cartridge. The valve includes a valve case having a guide bore and a valve pin moveably mounted to the valve case through the guide bore. The valve pin includes a large-diameter portion substantially disposed within the valve case and a small-diameter portion that is connected with the large-diameter portion and projects outward from the valve case. The valve case and the valve pin cooperate with the open end of the cartridge to define a gas passage for the fluid and liquefied CO.sub.2 gas flowing from inside of the cartridge to outside thereof. The gas passage includes an annular space between the large-diameter portion of the valve pin and an inner periphery of the valve case that defines the guide bore. A seal ring is fixed onto the valve case so as to project into the gas passage and interrupt the gas passage. When one end of the valve pin is in a non-depressed position, the large-diameter portion of the valve pin is in contact with the seal ring to thereby block the flow of gas passing through the gas passage. When the one end of the valve pin is depressed, the large-diameter portion of the valve pin is moved inward the cartridge to be free from the contact with the seal ring and a clearance is generated between the small-diameter portion of the valve pin and the seal ring. Thus, the flow of the fluid and liquefied CO.sub.2 gas is discharged and sprayed from the cartridge through the clearance that forms a part of the gas passage. An amount of the flow to be discharged per unit time is adjusted by determining the annular space between the valve pin and the valve case.
In the conventional art, the amount of the flow to be discharged from the cartridge per unit time is determined by a size of the annular space that is in the order of 0.01 mm. Namely, the size of the annular space is a size as small as those represented by a unit of 0.01 mm. If there is a slight error in the formation of the annular space, then the slight error will cause considerable dispersion of the amount of the flow to be discharged per unit time every valve and aerosol as a completed product. Further, the amount of the flow to be discharged will be reduced due to clogging of the annular space with the fluid upon stopping the discharge of the flow. This leads to unstable discharge of the flow from the cartridge.
It is an object of the present invention to provide a valve and an inhalator with the valve, capable of stably discharging a flow of fluid and pressurized gas as propellant that are stored in a container of the inhalator.